Mechanical Engineering Seminar

Mechanical Engineering Seminar

160 Convent Avenue, City College of New York
Department of Mechanical Engineering, Room ST-253

Location:

Steinman Hall 2nd floor

Phone Number:

2126505206

Secondary Phone:

2126505212

Admission Fee:

free

Event Details:

SEMINAR

DEPARTMENT OF MECHANICAL ENGINEERING

4D Printing with Shape-Shifting Materials

Prof. Howon Lee

Department of Mechanical Engineering and Aerospace Engineering

Rutgers University – New Brunswick

September 06, 2018

2:00 pm

Room T-254, Conference room of Mechanical Engineering

Abstract

Emerging pathway to create dynamic and adaptive structures involves additive manufacturing (often referred to as 3D printing) of soft active materials. This approach has been recently termed 4D printing, with the 4th dimension being time. In this work, Dr. Lee will present 3D micro-fabrication of stimuli-responsive shape-shifting materials using projection micro-stereolithography (PµSL). PµSL is a high-resolution digital 3D printing technique that utilizes the state-of-the-art digital display as a dynamically reconfigurable photomask to rapidly build complex 3D micro-structures in a layer-by-layer fashion. First, temperature-responsive swelling of 3D printed Poly(N-isopropylacrylamide) (PNIPAAm) hydrogel will be presented. Swelling ratio and transition temperature of 3D printed PNIPAAm is tailored by PµSL process parameters. Programmed deformation in highly complex 3D hydrogel micro-structures will be presented. He will also present soft robotic manipulation and locomotion with 3D printed electroactive hydrogel (EAH) micro-structures. Through 3D design and precise dimensional control enabled by PµSL, complex 3D actuations of EAH are achieved. Soft robotic actuations including gripping and transporting an object and a bidirectional locomotion in water will be presented. In the second part, he will present topologically reconfigurable, functionally deployable, and mechanically tunable lightweight metamaterials created through 3D printing of a shape memory polymer (SMP). The SMP is tailored to be as rigid as wood at room temperature, yet as soft as polystyrene foam at 90 °C. Using this ultra-tunable stiffness, lightweight tunable metamaterials that can control shock mitigation at an impact loading is demonstrated. Further, the SMP metamaterials can be significantly deformed and locked into an arbitrary geometry with the ability to fully recover the original shape on-demand. The reconfigurable and deployable lightweight structures maintain mechanical performance even after aggressive geometric reconfiguration and in various loading situations.

Bio: He received his PhD in Mechanical Engineering from the University of Illinois at Urbana-Champaign in 2011, followed by 3 years of postdoc training at MIT before he joined Rutgers University in 2014. He is currently involved in a wide spectrum of research areas including 3D/4D printing, soft materials mechanics, mechanical metamaterials, and biomedical engineering.